The present invention relates to a self-adjusting linkage for controlling a brake and more particularly relates to such linkage for controlling a brake of an external band type.
Control linkage for external band brakes are known which are the type including a pair of anchor pins respectively connected to the opposing end of a brake band and operative for anchoring one end of the brake band to the brake housing, when the brake drum is rotating in a first direction, while simultaneously moving the other end of the brake band towards the one end, and for anchoring the other end of the brake band to the housing, when the brake drum is rotating in the opposite direction, while simultaneously moving the one end of the brake band towards the other end. These linkages are constructed so as to dispose the brake band such that a desired gap exists between the brake band and the brake drum when they are in a released condition, and such that the band is moved a predetermined distance to cause its engagement with the brake drum when the actuating linkage is in an actuated condition. As a brake band wears, the desired gap between the band and the drum is no longer maintained and the linkage must be overtravelled to apply the brake band against the brake drum. While a certain amount of overtravel can be designed into the linkage it is usually more desirable, because of space limitations and the like, to maintain the amount of linkage travel within a predetermined range.
To minimize the effects of brake band wear on the operation of the control linkage, it is known to provide brake control linkages, with automatically adjust means which are responsive to the predetermined amount of movement of the control linkage beyond that necessary to cause full engagement of an unworn brake band to change the release condition distance between a brake band end so as to compensate for wear of the brake bands. Heretofore, the self-adjusting means have not been entirely satisfactory, due to their being complex and somewhat unreliable in operation.